I am the Male Lead's Ill Sister

Evangeline, who was reincarnated as the male lead’s younger sister, only had one year left to live. While her lovestruck pathetic brother followed the heroine to the ends of the earth, she decided to find the man of destiny who could save her. The only clue Evangeline was given was that he was blonde. With a plan in mind, she snuck out the mansion in anticipation of finding him. But somehow, things began to move strangely. Instead of fate, she kept running into a brown-haired boy who smelled fishy. “Will you take responsibility for my first time?” he said. He was too handsome to be a supporting character, Evangeline thought. Was he the emperor? Or a crook? There’s no way the author would give such beauty to a supporting character of a novel... Source: NU